Who was the greatest of the Greek tragedians? In The Frogs, Dionysus, the god of drama, crosses the River Styx to find out. Stephen Sondheim’s adaptation of the Aristophanes comedy doesn’t hold a candle to A Funny Thing Happened On the Way To the Forum, his previous foray into antique comedy. But the premiere at the Yale Swimming Pool, in 1974, was a historic occasion, the chorus packed with aspiring nobodies like Meryl Streep, Sigourney Weaver, and Christopher Durang. This was the year after the Broadway hit A Little Night Music; don’t ask about the acoustics or the reek of chlorine. Not until 2001 was there a recording. Thereupon, Nathan Lane threw his star power behind a much-expanded revival at Lincoln Center, directed by Susan Stroman. To coin a phrase, it croaked. Still, if you’re any kind of Sondheim fan, the MasterVoices concert version is a must. Count on Ted Sperling, artistic director, to cast the piece stunningly, to conduct his lush orchestra splendiferously, and to make you count your lucky stars that you had the sense to be there. For the record, Sperling singles out the number “Ariadne” as perhaps Sondheim’s most beautiful love song (more beautiful that “Loving You”?). There’s also “Fear no more the heat o’ the sun,” lyrics lifted from a little-performed Renaissance romance called Cymbeline. (Instead of a smackdown between Euripides and Aeschylus, Sondheim’s Frogs marshals Shaw and Shakespeare.) —Matthew Gurewitsch